Sunday, February 24, 2013

Apparently, shifting times differences measured with new and worn "10 speed" chains are marginally low to allow for any statistically significant conclusions. So I guess the message is don't fret unnecessarily over your chain length.

Speaking of chain wear, Wipperman's most conclusive test results on chain wear ranks themselves as number 1 in the list of 10 speed chains, which they attribute to their solid, no frills side plate and solid pins. Link.

Truly needed is an explanation of why belt drives are not par for the course in wet climates. I don't own a belt but have a natural antipathy for rain and the resultant mess in my links. I still ride however (79 inches in Palm Beaches last year and at least 76 are in my shoes!)

A couple of thoughts on the second part of this post regarding chain stretch under load.

First what are the typical loads on a chain for a "standard" rider weight for varying power levels? When riding on the flat at cruising speeds, momentum effects will mean that chain load is considerably less than for a standing start or when riding up hill.

Second, even if a chain does stretch. So what? Steel is elastic and generally behaves in accordance with Hooke's law:http://en.wikipedia.org/wiki/Hooke%27s_lawup until its proportional/elastic limit:http://en.wikipedia.org/wiki/Yield_%28engineering%29

The Wipperman information avoids addressing these points, so it's not clear how significant their data is to the real world aspects of cycling. This makes me wonder how much this is a case of selective use of the facts to push a marketing line.

Furthermore, when they point out that a stretched chain is a point of energy loss - fair enough. However, they don't go the further and critical step of showing what the energy loss is in quantitative terms measured by, say, Watts lost per mm stretched. Again, so what if the chain stretches?